Alternating current switch mechanism



Oct. 26, 1937. J. F, FRESE 2,097,403

ALTERNATING CURRENT SWITCH MECHANISM //L /a y /f 55@ ma Oct. 26, 1937. J. F. FREsE ALTERNATING CURRENT SWITCH MECHANISM Filed July 22, 1935 2 Sheets-Sheet 2 Patented Oct. 26, 1937 UNITED STATES PATENT OFFICE ALTERNAKTING CURRENT SWITCH MECHANISM Application July 22, 1935, Serial No. 32,663

3 Claims.

This invention relates to mechanism for operating two electric switches or two pairs of switches so as to open and close them alternately. The apparatus is adapted particularly for use on alternating current circuits and comprises a solenoid having a coil and an external laminated core -having two opposing pole pieces of like polarity and an armature movable between the pole pieces into and out of the coil. The armature is provided with a head adapted to fit flatly against the pole pieces. The armature is connected by springs to a rocking frame which directly operates the switches, and the frame is retarded in its movements by suitable retarding means. The arrangement is such that when the coil is energized the armature will be attracted and its head will nd its natural seat against the pole pieces without interference by contact with the frame, thus avoiding a humming noise which might occur if the head were not properly seated, and the frame will then follow, under the tension of the springs, retarded by the retarding means. The armature is provided with a stop or distance piece which normally rests against the frame and against which the frame rests when pulled upward by the springs. The frame and armature return to normal positions by gravity when the solenoid is deenergized. When the frame is moved by the solenoid it opens a pair of normally closed switches and closes a pair of normally open switches and when the frame returns by gravity to its normal position it closes the former pair and opens the latter pair of switches. The switch arms of both pairs of switches are under spring tension while closed, to maintain good electrical contacts with the stationary members `of the switches; but the arrangement is such that there is no spring tension to be overcome by the frame while the latter is returning to its normal position by gravity. Alsothere is no spring tension to be overcome by the frame while moving in the opposite direction, under the power supplied by the magnet until near the limit of the movement of the frame. Hence the springs associated with the switch arms do not hinder the rocking movement of the frame or apply an additional Vload on the armature of the solenoid until near the limit of movement of the frame, after the armature has been seated and there is plenty of power, supplied by the magnet, for operating the switches.

In the accompanying drawings,

Fig. 1 is a front elevation of the switch mechanism with the parts in their normal positions;

Fig. 2 is a right side elevation of the same;

(Cl. Z00-97) Fig. 3 is a section on the line 3--3 of Fig. 1, the parts being shown in normal positions in full lines and the armature being shown in its upper position in dotted lines;

Fig. 4 is a similar view with the parts in the positions which they occupy when the magnet is energized;

Fig. 5 is a section through one of the normally closed switches, taken on the line 5-5 of Fig. 1;

Fig-6 is a section through one of the normally open switches, taken on the line 6-6 of Fig. 1;

Fig. 7 is a similar view showing the switch closed;

Fig. 8 is an end view of the solenoid, and,

Fig. 9 is a side view of the armature.

Referring to the drawings, a indicates a sultable base of insulating material to the upper part of which is secured a bracket b. A solenoid c depends from the bracket, this solenoid comprising a laminated U-shaped core I having opposed pole pieces Ia of like polarity at its lower end, an internal energizing coil 2, and a movable armature 3 which extends between said pole pieces into the coil. 'I'he usual shading coil, embedded in the pole pieces, is indicated at 4. The armature y3 is laminated and angular in cross-section and has a head 3 which projects at its opposite sides and; is adapted to seat flatly against the pole pieces when the coil is energized. A fiat strip 5, preferably of non-magnetizable metal, projects outwardly from the center of the head 3a and this strip serves a purpose hereinafter described.

A pair of helical springs 6 connect the armature with a cross bar 8 on a rocking frame d. As shown, pins 9 project laterally from the center of the armature head, at its opposite sides, and the springs are connected to these and to the cross bar and normally hold the bar against the outer end of the flat metal strip 5, which is midway between the springs. The rocking frame comprises two similar side pieces IIJ rigidly connected together by an angled cross piece I I. Each side piece has a trunnion I2 and these trunnions are journaled in bearings I3 in supporting brackets I4. A flat relatively heavy bar I5, secured to the under side of' the flange IIa of the cross piece II, serves as a weight to rock the frame downwardly into the position shown in Figs. 1, 2, and 3, and ears IIJa on the side pieces of the frame are adapted to engage the upper edges of the brackets I4 and limit the downward movement of the frame. The side pieces have arms IIIb which project radially upward from the pivotal axis of the frame and these are connected by a round cross bar I6 which is adapted to engage and'operate a pair of switch arms e, e', which are normally closed, and another pair of switch arms f, f', which are normally open, as hereinafter explained.

A dashp-ot cylinder g is secured to the under and outflow of air to vary the retardation of the y plunger 253 in the cylinder, as desired. A rod 2l;

pivotally connected to the plunger at one end,l has at its opposite end a perforated head 2la through which the cross bar 8 on the rocking frame loosely extends. Y

The operation of the apparatus thus far described is as follows: When the coil of the solenoid is energized by the admission of alternating current thereto, the armature 3 is instantly ydrawn upward and its head 3a seats itself against the flat surfaces of the pole pieces and the` flat blade 5 is moved away from the cross barS, as indicated in dotted linesin Fig. 3. The rocking frame, retarded by the dashpot, moves upward by the traction of the springs 6, which are placed under tension by the upward movement of the armature, and when the frame reaches the position shown in Fig. 4, its movement is stopped by the engagement of th-e cro-ss bar 8 with the end of the blade 5 which constitutes a distance piece or stop. Thiseng'agement of the cross bar with the distance piece 4does not disturb the armature. By retarding the movement of the rocking frame, while permitting the armature to move freely upward, the head' of the armature will find its natural magnetic seat against the pole pieces without being hindered in this respect by any Contact with any part of Vthe frame and the humming noise which would occur if the head were prevented from finding its own seat is avoided. When the magnet is de-energized, its armature drops and since the stop or distance piece 5 is then in engagement with the cross bar 8, the frame is rocked -downwardly to normal position by the weight of the armature and the bar l5, the dashpot cushioning thismcvement, and the ears llla on the frame, engaging the brackets ld, limit the movement of the frame.

The switch arms e, e' are alike in structure and in their mountings, as are the contacts which they engage. One of these arms e, and the stationary contact 22 which it engages, is shown in Figs. 3, 4, and 5. The arm e has side flanges which are connected by a pivot pin 23 to a bracket 24 and a spring 25 coiled about the pivoty pin and having one end engaging the base of the bracket and the other end engaging the arm constantly presses the arm away from the base a so that the contact on the arm normally engages the stationary contact 22.

Normally the cross bar I6 on the rocking frame is out of engagement with the switch arms e, e

Vand these switches are closed, as shown in Figs.

3 and 5. When the magnet is energized, the frame is rocked an-d the bar presses against these switch arms and they are moved to open positions against the action of the springs 25, as illustrated in Fig. 4. There is abundance of power in the magnet for causing the opening of the Vswitches eze and when the magnet is de-energized, the springs move the switch arms to closed positions automatically and also, to a slight extent, assist the movement of the rocking frame Yto its normal position, at the commencement lof the movement. During the final part of the movement of the frame, cross bar i@ leaves the switch arms, as shown in Fig. 5.

l/Vhile the switches e, e are opened by the power of the magnet acting in opposition to the springs, and are self-closing by their springs when the magnet is zie-energized, the switches f, f' are closed by the power of the magnet but must be opened by the weight of the rocking frame and the armature when the magnet is de-energized. It is therefore desirable to avoid having spring pressure on the switches f, f which would resist their opening movements and oier resistance to the falling movement of the rocking frame and armature, because such spring pressure would have to be compensated for by making the weighted bar i5 heavier for strong spring pressure than would be necessary for light spring pressure, and it is desirable to have this weight relatively small and standard for all switches. Therefore, the arrangement of the springs on the switch arms f, f is such that they oiier practically no resistance to the movement of the rocking frame when the switches f' are being opened, and yet tension is applied to the springs by the force of the magnet when these switch arms are in closed positions. j

As shown in Fig. 6, the spring 25 is coiled around the pivot 2'! on which the switch arm f is mounted and one arm 2521 of the spring engages the cross bar i5 of the rocking frame, while the other arm 25h of the spring extends through an opening 28 in the switch arm and vpresses this arm against the cross bar, so that the switch arm and spring move together with the cross bar. the bar l@ moves from the position shown in Fig. 6 to that shown in Fig. '7, carrying the switch arm into position to engage the stationary contact 25 without applying tension to the spring and then continuing a short distance further, thereby applying sucient tension to the spring to provide a yielding contact between the switch members. When the magnet is de-energized and the rocking frame swings by gravity to its normal position, the bar i5 first relieves the tension on the spring and the spring and switch arm then move with the cross bar to the position shown in Fig. 6, free from spring resistance.

The mechanism is used as a timing device for controlling circuits. ed for use on alternating current circuits, it will be evident that it may be used on direct current circuits.

What I claim is:

l. In an electric switch mechanism, a switch member, a fra-me pivoted for roclnng movement about a stationary axis, for operating said member, said frame being biased to one position, a solenoid for rocking the frame to another position, said solenoid comprising a coil and an external stationary core having opposed pole pieces of like polarity at one end and an armature movable between said pole pieces into and out of the coil and having a head adapted to seat against said poleV pieces, said armature having a part normally engaging the frame and being movable away from the frame when the solenoid is energized, a spring connecting the armature with the frame, and means for retarding the movement of .the frame.

vabout a stationary axis, for operating said member, said frame being biased to one position, a

solenoid for rocking the frame to another posi- When the magnet is energized,

While it is especially adapttion, said solenoid comprising a coil and an external stationary core having opposed pole pieces of like polarity at one end and an armature move able between said pole pieces into and out of the coil and having a head adapted to seat against said pole pieces, a distance piece secured to the armature and normally resting against the frame, said armature and distance piece being movable away from the frame when the solenoid is energized, a spring connecting the armature with the frame, and means for retarding the movement of the frame.

3. In an electric switch mechanism, a switch member, a frame pivoted for rocking movement about a stationary axis, for operating said member, said frame being biased to one position, a solenoid for rocking the frame to another posi-l tion, said solenoid comprising a coil and an external stationary core having opposed pole pieces of like polarity at one end and an armature movable between said pole pieces into and out of thecoil, a distance piece secured to the armature and normally resting against the frame, said armature and distance piece being movable away from the frame when the solenoid is energized, a spring connecting the armature with the frame, and means for retarding the movement of the frame.

JOSEPH F. FRESE. 

